(a) Field of the Invention
The present invention relates to a device for hot stamping. More particularly, the present invention relates to a device and a method for hot stamping in which forming and cooling of steel heated to a set temperature are simultaneously performed to form ultrahigh strength steel.
(b) Description of the Related Art
Recently, use of ultrahigh strength steel has increased in the vehicle industry to decrease weight of vehicle body and improve safety. Ultrahigh strength steel is steel having tensile strength of over 1300 MPa. Particularly, the forming method of the ultrahigh strength steel having tensile strength of over 1500 MPa includes hot stamping.
Hot stamping is a method for manufacturing ultrahigh strength steel components with boron steel having high heat treatability. The boron steel may be heated to a temperature at which austenite may be formed. The austenite formed by heating the boron steel may be cooled and simultaneously formed so a phase thereof is transformed to martensite.
The hot stamping method is applied to ensure strength of a center pillar, a roof rail, a bumper, and an impact beam. Thus, reinforcements may be removed, thereby decreasing the weight of the vehicle body.
However, the whole component formed by the hot stamping is formed of martensite and adapted to have ultrahigh strength. Therefore, it may be difficult to trim a metallic pattern to form the edge and flange of the components by shearing to form a contour. In particular, if trimming is performed on the metallic pattern, many burrs may be generated at a fracture of the component. Additionally, impact absorbing performance may be deteriorated when the fracture of the component is large, causing cracks at the fracture. Further, the trimmed metallic pattern may break and mass production of the component may be difficult.
Alternatively, laser trimming without using the metallic pattern can be applied. However, manufacturing cost and processing time may increase using laser trimming.
The above information is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.